Heater



FIG. 1 is a perspective view of the heater showing my new design;

FIG. 2 is the front plan view;

FIG. 3 is a back plan view;

FIG. 4 is a left plan view;

FIG. 5 is a right plan view;

FIG. 6 is a downward plan view; and,

FIG. 7 is an upward plan view.

CLAIM The ornamental design for a heater, as shown and described.